The offence took place whilst the mother of three, from Chelford, Cheshire, was on bail after testing positive for the same drug following a tiff in December 2016 over phone messages about the former Manchester United manager and his family.

Ferguson - who was married to Sir Alex's son Darren - was convicted of the first drug driving offence in April but it is through the court were unaware of February's incident.

At Stockport magistrates this week she faced up to six months jail after admitting the second offence but escaped with a £300 fine and a three year road ban after telling how she had been encountering "significant difficulties."

Her lawyer Elizabeth Dyson, said: "Her reading was low and when police attended she cooperated in full with the officers there at the time. When she spoke to the police she explained that she had been socialising during the day before.

Nadine Ferguson was married to Sir Alex Ferguson's son Darren (Image: PA)

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"She was convicted in April this year and this offence was committed in February. But the circumstances of that first case were that she had applied for special reasons and exceptional hardship.

"Those court proceedings caused significant problems as she dealt with a lot of publicity at that time. She is a mother to three children who rely on her for day to day transport.

She added: "Miss Ferguson currently has ongoing civil proceedings causing difficulty to her financially, at present she finds herself in rented accommodation and works 16 hours per week in employment.

"She accepts the aggravating feature that court proceedings were ongoing at the time. She knows that disqualification level is to be extended today. She is very remorseful and embarrassed as she appears before the court again. She knows the publicity will secure that."

Ferguson was originally detained by police on December 17 2016 after officers were called to deal with an argument she was having with ex-boyfriend Ian Southworth at her former luxury barn conversion. She claimed she had found texts on Mr Southworth's mobile phone threatening to "expose' her ex-husband Darren, 46 and members of his family.

But she was asked to take a breath test when police called by Mr Southworth saw Ferguson driving her Range Rover Evoke to his cottage opposite her home on a stud farm in Mobberley, near Knutsford, Cheshire to return the device.

Inquiries revealed she was under limit for drink driving but was four times the limit for drug driving with officers discovering she had 200mg of Benzoylecgonine - the metabolite of cocaine - in her system. The drug driving limit is 50mg.

In April at Manchester she was disqualified for a year and fined £120 and ordered to pay £235 in costs and surcharges. In court she claimed she was having to work as a barmaid and go back to a family court after she said £1,000 per month for child maintenance had stopped.

But on Monday prosecutor, Sonia Alford said: "On Thursday 15 February at 6.55pm police officers were on patrol when they saw a grey Mercedes parked in a lay-by in Alderley Edge and the displayed registration plate was registered to a company.

"They decided to follow the car along to the A34 Wilmslow Road. The speed limit on that stretch of road is 70mph and the vehicle was being driven at 40mph and weaving between lanes one and two.

"They approached the vehicle from behind and signalled to stop which it did. They spoke to the driver, which was this defendant and she said she was driving a friend's car. Relevant checks were made and she was correct.

"Due to the manner of the defendants driving the officers conducted a road side drug test. She presented a reading of 57mg/l, with the limit being in 50mg/l blood. The defendant committed a previous drug driving offence but wasn't convicted of that offence until April this year.

"When she committed this offence on 15 February she was on bail for the similar offence of drug driving, which is a seriously aggravating factor."

JPs also ordered Ferguson to pay £115 costs and pay off the at £100 a month. She told the court: "I will be working full time, I've just started another job. I will pay all of it off."

Ferguson has a 15-year-old daughter Grace, with Darren, 45, who raised her son from another relationship, Charlie, now 18, as his own.

In 2009, Ferguson and Charlie were involved in a horror crash during a school run, in Oldham. Charlie suffered life-threatening internal injuries. He broke his back and was in a coma for three days, while his scalp was severed nearly all the way round.

Ferguson's femur was broken in 35 places and doctors considered amputation. She also broke eight ribs. But both mother and son made a recovery from their horrific injuries.